This invention relates to semiconductor modules. Particularly, this invention relates to semiconductor modules with very compactly mounted semiconductor chips.
FIG. 12A and FIG. 12B show the structure of this type of semiconductor module. FIG. 12A is a top view and FIG. 12B is a side view of the conventional semiconductor module. This semiconductor module is made of a semiconductor package 1 mounted on either side of a substrate 2. The semiconductor package 1 is obtained by sealing a not shown semiconductor chip with a seal 1a. The semiconductor package 1 is mounted on the substrate 2 using external leads 1b. Moreover, external connecting terminals 5 are provided on the substrate 2.
FIG. 13A and FIG. 13B show ways in which the semiconductor module shown in FIGS. 12A and 12B can be mounted. FIG. 13A shows an example in which two semiconductor modules are mounted next to each other whereas FIG. 13B shows an example in which the two semiconductor modules are stacked one on top of another. These semiconductor modules perform desired functions when they are connected to the motherboard 9 via external connecting terminals 5, 5xe2x80x2.
There has been a demand for small sized, slim, high performance electronic gadgets in the past year, contrary to the preceding years. The important question here would be how to pack semiconductor chips compactly in order to make the electronic gadget small and slim.
However, if a plurality of semiconductor modules are arranged side by side as shown in the FIG. 13A, the motherboard 9 on which the semiconductor modules are to be mounted will have to have sufficient surface area to accommodate the sate semiconductor modules. Thus, the mounted semiconductor package 1 (semiconductor chip) would still not be compact enough.
If the semiconductor modules are packed one on top of another as shown in FIG. 13B, they would occupy less surface area on the motherboard as compared to the side-by-side arrangement.
However, when multiple semiconductor modules are to be stacked one on top of another, there should be enough space between the adjacent semiconductor packages. This space is mandatory to avoid any kind of damage to the semiconductor modules because of their mutual contact due to heat generation or vibration.
Consequently, it is necessary to lengthen the external connecting terminals 5 of the upper semiconductor module. This may reduce the rigidity of the external connecting terminals 5 thereby making it difficult to fix the upper semiconductor module to the motherboard 9.
The external connecting terminals 5 of the upper semiconductor module will have to be placed externally to the external connecting terminals of the lower semiconductor module. As the number of layers of semiconductor modules increases, the surface area of the motherboard increases to the extent required for fixing the external connecting terminals 5.
It is an object of this invention to provide a semiconductor module in which semiconductor chips are mounted compactly and reliably.
The semiconductor module according to one aspect of this invention comprises a plurality of substrates connected serially through a flexible cable and stacked together, wherein semiconductor chips are mounted on at least surfaces facing each other of the substrates, and the semiconductor chips of adjoining one of the substrates being bonded to each other.
According to the above aspect, a plurality of substrates with semiconductor chips mounted on them are stacked together. Furthermore, these semiconductor chips of adjoining substrates are bonded to each other and thereby held in position. Therefore, there is no possibility that the chips come in contact with each other, moreover, the substrates can be stacked with minimum space between them.
In the above-mentioned semiconductor module, at least one of an outermost substrate in the stacked substrates is provided with external connecting terminals by which the substrate can be mounted on the motherboard.
Thus, the semiconductor module can be mounted on the motherboard using the external connecting terminals provided on the outermost substrate.
In the above-mentioned semiconductor module, the external connecting terminals are leads extending outward from the outermost substrate.
Thus, the semiconductor module can be mounted on the motherboard using the leads provided on the outermost substrate.
In the above-mentioned semiconductor module, a plurality of sockets corresponding to the external connecting terminals of the substrates are provided on the motherboard, wherein the external connecting terminals are connector pins that can be inserted into or removed from the sockets provided on the motherboard.
Thus, the semiconductor module can be attached to or detached from the motherboard by connector pin-socket arrangement.
In the above-mentioned semiconductor module, the external connecting terminals are bumps that aid mounting of the module on the surface of the motherboard.
Thus, the semiconductor module can be mounted on the surface of the motherboard utilizing the bumps.
In the above-mentioned semiconductor module, the outermost substrate on which the bumps are provided is also provided with dummy members for smoothening out distortions that occur in the bumps.
Thus, dummy components are provided for smoothening out the distortions of the bumps.
The above-mentioned semiconductor module comprises external connecting terminals for mounting the substrates upright on the motherboard.
Thus, external connecting terminals are provided to mount the semiconductor module to the motherboard, and thereby the substrates can be mounted upright on the motherboard.
In the above-mentioned semiconductor module, the external connecting terminals are provided at ends of the substrates that are held in place with respect to each other.
Thus, the substrates are held in place with respect to each other on the motherboard.
In the above-mentioned semiconductor module, the external connecting terminals are leads that extend outward from the substrate.
Thus, leads are provided to mount the semiconductor module on the motherboard.
In the above-mentioned semiconductor module, a plurality of connectors corresponding to the external connecting terminals of the substrates are provided on the motherboard, wherein the external connecting terminals are connector terminals that can be attached to or removed from the connectors provided on the motherboard.
Thus, a connecting terminal-connector arrangement is provided so that the semiconductor module can be attached to or removed from the motherboard.
In the above-mentioned semiconductor module, the ends of the substrates on which the connector terminals have been mounted protrude beyond the ends of other substrates.
Thus, ends of the substrates on which the connector terminals are mounted are lower than the ends of the other substrates.
In the above-mentioned semiconductor module, the semiconductor chips are mounted on the substrate using external leads.
Thus, the semiconductor chips are mounted on the substrate by external leads.
In the above-mentioned semiconductor module, the semiconductor chips are mounted on the surface of the substrate.
Thus, the semiconductor chip is surface-mounted on the substrate.
In the above-mentioned semiconductor module, the semiconductor chips are mounted on the substrate using bare chip technology.
Thus, the semiconductor chips are mounted on the substrate using bare chip technology.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.